Many different types of rotary devices have been suggested in the past and have been covered by a large number of patents. In the field of rotary engines, the best known is the Wankel engine that has been in volume production in Mazda automobiles. This engine has had considerable difficulties with proper sealing of the rotors, although such problems have been largely overcome.
Another type of rotary device is referred to herein as the “rotary axial vane” device. This type of device has a rotor located within a cylindrical chamber defined in stator housing. A plurality of blade-like vanes extend slideably through the rotor, parallel to the rotor axis of rotation. The stator housing is closed by end walls, the inner faces of which define an undulating, cam surface on each side of the rotor High portions of the cam surface furthest away from the rotor on one side align with low portions of the cam surface on the opposite side of the rotor. Rotation of the rotor causes the chamber defined between adjacent vanes, the rotor and the end wall to expand or decrease as the vanes approach a low point or high point of the cam surfaces thus expanding or compressing a fluid between the adjacent vanes. Devices of this type have been long used as steam engines, compressors and expanders. More recently interest as shown in these devices as internal combustion engines.
For example, one such engine is described in U.S. Pat. No. 4,401,070, issued Aug. 30, 1983 to James Lawrence McCann. This type of engine compresses gases forwardly of each vane in the direction of rotation as the rotor rotates. The compression occurs as the vane moves from a low cam surface, relatively distant from the rotor, to a high cam surface relatively close to the rotor. After the gases are compressed, they must be transferred to the rearward side of each vane prior to combustion so that the ignited gases will propel the rotor forward.
The need for transferring the compressed gases is removed in a variation of the type of rotary engine such as found in Polish Patent #38112 to Czyzewski. In this case, the gases are compressed between adjacent vanes which are angularly spaced apart more closely than in the McCann engine. The gases are compressed as each pair of adjacent vanes moves toward a high cam area. Expansion of the ignited gases creates a propulsion force as the vanes continue to move past the high cam area to a relatively low cam area after ignition.
This type of rotary engine offers many potential advantages including high efficiency, simple construction and lightweight. However, while the theoretical possibilities of such an engine have been suggested in the past, many practical difficulties have inhibited development of these engines beyond the stage of the working prototype. Only a relatively small number of these have been thoroughly tested. Many rotary devices such as engines are of interest on paper, but practical difficulties arise when prototypes are constructed. Of particular interest are axial vane rotary internal combustion engines. Theoretically these engines should be highly efficient and the relatively small size for the horse power output that should be generated. Only a relatively small number of these have been thoroughly tested. For example, some earlier patents do not disclose any practical system of seals between the rotor, vanes and stator. In addition, relatively high loads can occur on the tips and seals of the vanes that can cause premature wear.
Some of these problems have been overcome by an improved axial vane engine as described in U.S. Pat. Nos. 5,509,793, 5,551,853 and 5,429,084 to Cherry, et al. The axial vane devices of the type described in these patents find use not only as engines but also as pumps, expanders and compressors. The chamber pressures are substantially higher than were encountered with the older devices referred to above that dealt with steam as the fluid being acted on by the device. Cherry et al. in the aforementioned '084 and '853 patents attempted to provide seals for the axial vane devices. It has been found, however, that the seals are difficult to make and install and add substantially to the manufacturing and the maintenance costs of the axial vane devices and most importantly, despite the provision of seals, leakage between the rotor and the outer housing of the rotor is substantial resulting in engines which are essentially inoperative.
Accordingly, it is an object of the invention to provide an improved axial vane device that overcomes the leakage problems associated with earlier axial vane devices.
It is another object of the invention to provide an axial vane device that is easier to manufacture and which requires less maintenance.
Yet another object of the invention is to provide an axial vane device in which wear on the axial vanes is reduced.